You’re right, there’s no getting around the problem of hard solipsism. But in the context of being able to observe evolution, solipsism in general gets destroyed as a framework. The two cannot coexist — if solipsism is real then evolution was designed by my mind to trick me. If evolution is true (which we have evidence to believe it is), then solipsism cannot exist, because there are in fact real other organisms competing biologically.
I’m not just assuming the world I see is real. I have reasons to believe there is a world outside my brain. What I am NOT doing is making a claim that any other world exists. Only that in a normal state, my brain converts physical stimuli into feelings, experiences, and I recognize my brain is immensely complex and things can change that experience.
If you claim to experience a spiritual world, you have to explain how it differs from the physical world. So far you haven’t. You’ve just referenced people you think can.
Otherwise, to me, spirituality is the realm of my brain feeling funny, but I have no reason to believe I’m communicating with any entity other than my own brain.
You mention I believe this because of the culture I was brought up in. I agree. I also think that my current culture is the most correct one so far because the scientific method drives how I inform myself. While the method doesn’t claim to prove anything for absolute certain, it does require well-formed questions and substantive answers. In the framework of science, spirituality can only be described as an internal brain state, because a world of forms is not a well-formed question.
Consider the culture of the first spiritual. Their brains went haywire and they already believed in spirits. Perhaps the ancients were the ones in error; I find this likely given their relative ignorance, proclivity for assigning natural phenomenon to gods, and complete lack of understanding of mathematics.
Today we stand on stronger epistemological grounds, it pains me to see people reject it in favor of ancient ignorance and fanciful stories; nearly everyone seems to believe most of these stories are false, except their own. I just gave up my people’s story too.
